In 2006, Tango's book The Book: Playing the Percentages in Baseball, which was co-written with Mitchel Lichtman and Andrew Dolphin, was published featuring a foreword by Pete Palmer. In The Book he and his coauthors analyzed many advanced baseball questions, like how to optimize a lineup or when to issue an intentional base on balls. They also introduced the wOBA metric to measure overall offensive contributions.[2]

Tango maintains the "Marcel the Monkey Forecasting System," a player projection system which uses three years of weighted player statistics with statistical regression and player age adjustment.[3]

He is best known for developing the FIP (Fielding Independent Pitching) statistic, which attempts to more accurately assess the quality of a pitcher's performance than other statistics, such as ERA. 2009 American LeagueCy Young Award winner Zack Greinke specifically mentioned FIP as his favorite statistic. "That's pretty much how I pitch, to try to keep my FIP as low as possible".[4]